1. Average/Instantaneous Velocity/Speed
Physics 513

2. Let’s Try This One Together
A car travels in the +􏰄x-direction on a straight and level road. For the first 4.00 s of its motion, the average velocity of the car is
= 6.25 m/s. What is the car’s displacement after 4.00 s?

3. Let’s Try This One Together Too
Starting from the front door of your ranch house, you walk 60.0 m due east to your windmill, and then you turn around and slowly walk 40.0 m west to a bench where you sit and watch the sunrise. It takes you 28.0 s to walk from your house to the windmill and then
36.0 s to walk from the windmill to the bench. For the entire trip from your front door to the bench, what is your average speed?

4. Let’s Think This Through Together…
Does the speedometer of a car measure speed or velocity? Explain

5. Let’s Discuss the Direction of Motion
Positive Negative

6. Let’s Think About This One
The figure on the next slide is a position vs. time graph of the motion of a particle.
(a) Rank the values of the particle’s x-velocity at the points P, Q, R, and S from most positive to most negative.
(b) At which points is positive?
(c) At which points is negative?
(d) At which points is zero?
(e) Rank the values of the particle’s speed at the points P, Q, R, and S from fastest to slowest

7. Figure